Rooftop air-conditioning installations have basically been known for a long time for busses. They usually comprise a condenser unit and one or more evaporator units and communicate with the passenger compartment of the bus by flow technology in order to supply it with fresh air. The supplied air can be heated or cooled by the rooftop air-conditioning installation.
Generic, published prior art has been published, for example as DE 10 2007 023 249 A1 or DE 60 2004 006 988 T2.
Usually, several double radial fans with fan wheels which are curved forward in a completely spiral housing are used in the evaporator units used which transport an air flow in an air flow duct through the heat exchanger into the passenger compartment. The air flow is deflected several times, in particular during the intake, in the radial fan itself, during discharge and when conducted further. This has a negative effect on the efficiency of the air conditioning installation. At the same time the current consumption of the electromotors driving the radial fans rises and with it the fuel consumption of the vehicle.